The present invention relates to casted concrete block manufacturing and, more particularly, to an apparatus and method for roughing blocks to give them a worn or rough appearance.
The concrete block casting industry is well developed and is highly automated in its process operations for manufacturing conventional rectangular concrete blocks and the like. The casted blocks have a geometrically uniform rectangular prism configuration in which the surfaces thereof are substantially planar with adjacent surfaces delimited by sharp edges.
It has been known to treat the concrete blocks in order to get a more natural rough look. As authentic stone blocks are known to have rounded edges and irregular shaped surfaces, systems have been provided in order to produce such effect on casted concrete blocks. However, the equipment used in order to treat these blocks has been incompatible with the fully automated handling equipment used in the other operations of the concrete block producing process. Substantial amount of manual labor and high costs are inherent with the presently used block roughing systems.
For instance, a known method consists in disposing the casted blocks in large tumbling drums. These tumbling drums are rotated about their longitudinal axis in order for the concrete blocks to tumble therein and to collide in order to get damaged. This method, although producing a generally satisfying look, entails substantial costs due to unrepairable damages to concrete blocks. Some blocks are damaged to a point where they may no longer be used and are thus thrown away or recycled. Also, some concrete block patterns may contain blocks of different sizes and these must be sorted and assembled, which is very time consuming. Also, if a particular one of the blocks in pattern is destroyed more than other blocks, then often the other blocks are no longer useful as a ratio of blocks must be kept. By its nature, the tumbling drum requires frequent repairs. Furthermore, the personnel used for these purposes must deal with a noisy environment due to the tumbling action, and injuries are frequent due to the hazardous operations and handling required thereby. It is difficult to maintain a stable labour force for this work.
U.S. Pat. No. 5,133,915, issued on Jul. 28, 1992 to Metten et al., discloses a surface upon which a plurality of concrete blocks are disposed in a spaced apart relationship. A roller brush translates over the surface of concrete blocks in a reciprocating manner, thereby stripping and roughing the surface of the concrete blocks. Although this method provides substantial advantages over the tumbling drum method described above, it requires that the concrete blocks are spaced apart in order for the sharp edges thereof to be treated. Otherwise, only the top surface would be abraded. Furthermore, the brush type roller provides a relatively uniform abrasion of the concrete blocks, which is not a desired result for use with paving blocks. Finally, as the concrete blocks are spaced apart, the brush can only strike them at a certain velocity in order not to displace them. If they are displaced, they may end up in abutment with one another, whereby only the top surfaces will be abraded, leaving the sharp edges of the block intact. These blocks are usually treated before the concrete is cured. This patent could not provide the desired result of producing an irregular roughened appearance to concrete blocks.
It is a feature of the present invention to provide a concrete block roughing apparatus and method which substantially overcomes the disadvantages of the above mentioned prior art.
According to the above features, from a broad aspect, the present invention provides an apparatus for roughing at least one of surfaces and edges of solid concrete casted blocks, comprising a block support surface having at least two surface sections. The surface sections have straight front and rear end edges disposed parallel to one another. A first of the surface sections has at least its rear end edges thereof above an adjacent front end edge of a second of the surface sections to create a ledge for projecting a leading edge portion of concrete blocks conveyed over the first surface section. A roughing device is supported a predetermined distance above the block support surface and has a plurality of impacting elements thereon for roughing concrete blocks in a non-uniform fashion. The first roughing device is disposed generally above the rear end edge of the first surface section for abrading a projecting leading edge portion of each concrete block as they are conveyed over the rear end edge. Conveying means displace the concrete blocks over the first and second surface sections, the blocks being tilted when reaching a predetermined position over the ledge to avoid being abraded by the roughing device.
According to a further broad aspect of the present invention, there is provided a method for roughing portions of concrete casted blocks comprising the steps of (i) providing a block support surface having at least a section thereof inclined to create a ledge for projecting a leading edge portion of concrete blocks conveyed over the ledge by conveying means; (ii) providing at least a roughing device having a plurality of impacting elements thereon and disposed at a predetermined position above the ledge; and (iii) impacting the leading edge portions of the concrete blocks by the roughing device as they are projected over the ledge by the conveying means, the blocks being tilted when reaching a predetermined position over the ledge to avoid being abraded by the roughing device.